Voltage-regulating system



1957 H. A. ENGLE 2,808,559

- VOLTAGE-REIGULATING SYSTEM Filed Sept. 20, 1954 HOMER A. ENG-L. E

INVENTOR.

United States Patent VOLTAGE-REGULATING SYSTEM Homer A. Engle, LosAngeles, Calif., assignor, by mesne assignments, to Viking Industries,Inc., Canoga Park, Califl, a corporation of California ApplicationSeptember 20, 1954, Serial No. 457,180

2 Claims. (Cl. 323-21) This invention relates to voltage-regulatingsystems and, more particularly, to improvements therein.

A feature of the present invention is the provision of a system forregulating alternating current voltages.

Another feature of this invention is the provision of a novel and usefulregulating system.

Still another feature of the present invention is the provision of aregulating system which can be employed for regulating voltages over anextensive range of load currents.

These and other features of the invention are provided in a systemwherein each of two gas tubes has a saturable reactor control windingconnected between its anode and its cathode. The tubes are biased by analternatingcurrent priming bias which positions them at conduction. Aload may be connected to the anodes of the gas tubes.Alternating-current operating potential is applied between the cathodesand through the load to the anodes of the two gas tubes. Voltage-controlmeans consisting of an electric light is coupled across the load in amanner so that variations in the voltage being supplied to the loadcause fluctuations in the intensity of the light. A photocell orphototube is positioned to receive light from the electric light. Itsoutput is a voltage which varies with the intensity of the light. Thisphotocell output is applied to the control grids of the two tubes as abias which opposes the previously described priming bias. Thisadditional bias causes the gas tubes to conduct in a manner so that thevoltage which is applied across the load is maintained substantiallyconstant. In effect, what is provided here is a means of obtainingregulation, in which fluctuations either caused by variations in theload or even due to some variations in source of supply are minimized.

The novel features that are considered characteristic of this inventionare set forth with particularity in the appended claims. The inventionitself, both as to its organization and method of operation, as well asadditional objects and advantages thereof, will best be understood fromthe following description when read in connection with the accompanyingdrawing, which is a circuit diagram of the embodiment of the invention.

Referring now to the figure, there may be seen a pair of gas tubes 10,20. These are preferably of the grid-controlled type such as athyratron, having an anode 12, 22, a control grid 14, 24, and a cathode16, 26. A saturable reactor 18, 28 is connected by means of its controlwinding between the anode and cathode of each tube. A priming bias isprovided to both tubes, to render them conducting, from a transformer30, which has primary winding 32 and a secondary winding 34. An A. C.voltage is applied to the primary of the transformer from a source 36which is connected through a stepdown transformer 38 to twopotentiometers 40, 42. These potentiometers are connected in the mannerof a resistance bridge and have their sliders connected to the primaryof the transformer 30. The transformer secondary is connected to boththe control grids 14, 24

of the gas tubes. A load 46 is connected to the anodes of both gastubes. Operating potential for the tubes is connected from the source 36to the load and to the cathodes of the gas tubes.

As thus far described, the circuit essentially resembles the one shown,described, and claimed in an application for a Control System by thisinventor bearing Serial Number 420,349 and filed April 1, 1954. Theoperation of the system shown thus far is substantially as described inthe application, namely, the gas tubes, when biased to conduct, havetheir impedances reduced considerably. The saturable reactors each has ahigh impedance when no D. C. is passing through its control winding.When the gas tube conducts, a certain amount of D. C. circulates betweenit and the control winding of the saturable reactor connectedthereacross, thus reducing the impedance of the reactor. Thus, thecurrent which passes through both tube and saturable reactor isconsiderably greater, due to the two low-load impedances in parallel,than would pass either through the tube alone or the saturable reactoralone. When the gas tube is not conducting, its impedance is high and,in view of the fact that no D. C. flows through the saturable-reactorwinding at that time, its impedance is also high. Thus the circuit cancontrol a considerably larger current flow with these connections thanby using either the tubes alone or the saturable reactors alone. Adetailed description of the operation of the control system may be foundin the previously mentioned application. Therein also there is shown howa regulatory operation of a servo type is made possible when the loadconsists of the field windings of a motor and the shaft of the motor iscoupled to one of the potentiometers 42, 40 in a manner to restore thebalance of the bridge when an unbalance occurs.

The regulatory operation in the present embodiment of the invention isprovided by means of an electric light 50, which is coupled across theload by means of a stepdown transformer 52. A photocell 54, which mayalternatively be a phototube if amplification is desired, receives lightfrom the electric light 50. The photocell is biased by means of battery56 and control resistor 58 in a well-known manner. Accordingly, lightvariations cause the current flowing through the photocell to vary inaccordance therewith. Since the photocell is also connected to thesecondary winding 34, the variations of bias are communicated to thegrids of the gas tubes where, in combination with the priming bias, theycontrol the current flow through the gas tubes. The bias supplied fromthe photocell is applied with a polarity to increase the flow of currentwhen there is a decrease in the light output. Thus the photocell biasopposes the priming bias. The effect of the light and photocell feedbackregulation is to increase considerably the sensitivity of the voltagecontrol arrangement while providing an inexpensive feedback system. Thelight employed was a standard commercially obtainable light source forwhich the stepdown transformer reduced the applied voltage to the regionof one-half its rated operating voltage. This portion of the lightsource characteristic displays excellent linearity with variations inthe fluctuations of the voltage applied to the primary of thetransformer 52, while the thermal inertia of the filament is notaffected by the powerline frequency fluctuations. The system wasoperated at both 60-cycle and 400-cycle frequencies and displayedexcellent regulatory characteristics. The range of control is fairlyextensive and may be adjusted for different values of output voltagefrom the anodes of the gas tubes by adjusting the output voltage oftransformer 52 to maintain the voltage applied across the electric light50 within the region wherein its character is substantially linear withvoltage variations.

While two gas and two saturable reactors are shown 0 and describedherein, it will be appreciated that it is Within the scope of thisinvention to use one tube and one saturable reactor, two tubes and onesaturable reactor, or any combination of different numbers of tubes andsaturable reactors to achieve the required regulation of voltage andcurrent.

Accordingly, there has been described and shown herein a novel, simple,and useful system for controlling the output voltage from analternating-current source.

I claim:

1. A voltage-control system comprising a pair of tubes each havinganode, cathode, and control electrodes, a pair of saturable reactors,each of which is connected between anode and cathode of a different oneof said tubes, means to apply a load to said anodes, means to apply anoperating potential between said anodes and cathodes, an electric light,means to couple said electric light to produce fluctuation of said lightoutput with variations in potential at said means to apply a load,photocell means to generate a regulatory bias responsive to saidfluctuations of said light, means to apply a priming bias to saidcontrol grids including a transformer having a primary winding and asecondary winding, said control grids being respectively coupled to oneend of said secondary Winding, and means to apply said regulatory biasto said control grids including connections between said photocell meansand said secondary winding to control said tubes to compensate for saidpotential variations.

2. In a voltage-control system of the type including a pair of gas tubeseach having a control grid, an anode, and a cathode, each having asaturable reactor connected between said anode and cathode, atransformer having a secondary winding, said control grids being coupledto said secondary winding, means to apply a priming bias to the primaryWinding of said transformer, and means to apply operating potential tosaid gas tubes, the improvement comprising apparatus to regulate thevoltage output of said gas tubes including an electric light, atransformer coupling said electric light to said anodes to deriveilluminating current therefrom, photocell means exposed to said light togenerate a regulatory bias varying responsive to variations inillumination, and means to apply said regulatory bias to said secondarywinding to control said gas tubes to substantially eliminate saidvariations in illuminating current.

References Cited in the file of this patent UNITED STATES PATENTS

